Personally, I think number one would be a no-no, since your main motivation to do so is to benefit another player, and thus, interfering in the natural progression of the game. As for dealing with this though, true, the second player has a VERY low chance of winning due to this situation. Changing his role to survivor wouldn't be a bad way to fix it, given the info you've provided. So long as doing so doesn't unbalance the game in some way. Biggest thing I'd stress to this player is that they are not to discuss in thread their previous win and that this has changed, since it would interfere with the game for players to believe any cult mechanic isn't an issue anymore. Perhaps change his win to this: "Wins if they survive til the end of the game, bonus win if culted and the cult wins."